Hi,i bought a set of upgraded lifters to Cosworth YB and got big problems. The lifters were still noisy after a few houres. After a few days i took the camshafts of and one lifter wouldnt out. And there was many deep scratches in 4 of the tappet holes(exhaust side). Oil pressure is 35-40psi at idle and 70psi at 4000-6000rpm warm engine(high pressure oil pump). What can cause this problem and is it possible to find oversized lifters to Cosworth yb engine.